Zera is a Heartless - the immortal, unageing soldier of a witch. Bound to the witch Nightsinger ever since she saved her from the bandits who murdered her family, Zera longs for freedom from the woods they hide in. With her heart in a jar under Nightsinger's control, she serves the witch unquestioningly.

Until Nightsinger asks Zera for a Prince's heart in exchange for her own, with one addendum; if she's discovered infiltrating the court, Nightsinger will destroy her heart rather than see her tortured by the witch-hating nobles.

Crown Prince Lucien d'Malvane hates the royal court as much as it loves him - every tutor too afraid to correct him and every girl jockeying for a place at his darkly handsome side. No one can challenge him - until the arrival of Lady Zera. She's inelegant, smart-mouthed, carefree, and out for his blood. The Prince's honor has him quickly aiming for her throat.

So begins a game of cat and mouse between a girl with nothing to lose and a boy who has it all.

Winner takes the loser's heart.

Literally.